Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by engines (e.g., IC engines). Conventional exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) catalyst to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3). Generally in such conventional aftertreatment systems, an exhaust reductant, (e.g., a diesel exhaust fluid such as urea) is injected into the aftertreatment system to provide a source of ammonia, and mixed with the exhaust gas to partially reduce the NOx gases. The reduction byproducts of the exhaust gas are then fluidically communicated to the catalyst included in the SCR aftertreatment system to decompose substantially all of the NOx gases into relatively harmless byproducts which are expelled out of such conventional SCR aftertreatment systems.
In conventional aftertreatment systems, liquid exhaust reductant is atomized into droplets and inserted into a stream of exhaust gas. Conventional aftertreatment systems therefore generally include exhaust reductant dosing modules which include actuators, atomizers (e.g., air assisted injectors), and other components to produce a desired droplet size which can efficiently mix with the stream of exhaust gas. The liquid reductant droplets can however, crystallize and deposit on the walls or catalyst of the SCR system, or otherwise the components of the aftertreatment system. This can reduce the efficiency of the aftertreatment system, increase backpressure experienced by the exhaust gas, lead to increased NOx emissions and increase in warranty claims. Therefore conventional aftertreatment systems include complex technologies for producing exhaust reductant droplets having a desired size to obtain optimum evaporation, and reduce exhaust reductant deposits which adds complexity and increases the overall cost of the aftertreatment system.